控制台脚本执行时出现 ModuleNotFoundError

Question

怎么了

我有一个用 Python 3（Python 3.6.0 解释器）编写的简单 CLI 项目，我可以直接从命令行使用包和模块名称运行它，但在安装时失败setuptools：

# success
? python -m myProject.cli --version
0.0.1.dev0

# failure
? mycli --version
Traceback (most recent call last):
  File "/path/myProject/venv/bin/mycli", line 11, in <module>
    load_entry_point('myProject==0.0.1.dev0', 'console_scripts', 'mycli')()
  File "/path/myProject/venv/lib/python3.6/site-packages/pkg_resources/__init__.py", line 560, in load_entry_point
    return get_distribution(dist).load_entry_point(group, name)
  File "/path/myProject/venv/lib/python3.6/site-packages/pkg_resources/__init__.py", line 2648, in load_entry_point
    return ep.load()
  File "/path/myProject/venv/lib/python3.6/site-packages/pkg_resources/__init__.py", line 2302, in load
    return self.resolve()
  File "/path/myProject/venv/lib/python3.6/site-packages/pkg_resources/__init__.py", line 2308, in resolve
    module = __import__(self.module_name, fromlist=['__name__'], level=0)
ModuleNotFoundError: No module named 'myProject'

项目设置

该项目具有以下结构：

.
??? myProject
?   ??? cli.py
??? setup.py

我期待mycli稍后安装脚本，因此我setup.py看起来像这样：

.
??? myProject
?   ??? cli.py
??? setup.py

安装

安装完成，没有错误：

? python setup.py install
running install
running bdist_egg
running egg_info
writing myProject.egg-info/PKG-INFO
writing dependency_links to myProject.egg-info/dependency_links.txt
writing entry points to myProject.egg-info/entry_points.txt
writing requirements to myProject.egg-info/requires.txt
writing top-level names to myProject.egg-info/top_level.txt
reading manifest file 'myProject.egg-info/SOURCES.txt'
writing manifest file 'myProject.egg-info/SOURCES.txt'
installing library code to build/bdist.macosx-10.12-x86_64/egg
running install_lib
warning: install_lib: 'build/lib' does not exist -- no Python modules to install

creating build/bdist.macosx-10.12-x86_64/egg
creating build/bdist.macosx-10.12-x86_64/egg/EGG-INFO
copying myProject.egg-info/PKG-INFO -> build/bdist.macosx-10.12-x86_64/egg/EGG-INFO
copying myProject.egg-info/SOURCES.txt -> build/bdist.macosx-10.12-x86_64/egg/EGG-INFO
copying myProject.egg-info/dependency_links.txt -> build/bdist.macosx-10.12-x86_64/egg/EGG-INFO
copying myProject.egg-info/entry_points.txt -> build/bdist.macosx-10.12-x86_64/egg/EGG-INFO
copying myProject.egg-info/requires.txt -> build/bdist.macosx-10.12-x86_64/egg/EGG-INFO
copying myProject.egg-info/top_level.txt -> build/bdist.macosx-10.12-x86_64/egg/EGG-INFO
zip_safe flag not set; analyzing archive contents...
creating 'dist/myProject-0.0.1.dev0-py3.6.egg' and adding 'build/bdist.macosx-10.12-x86_64/egg' to it
removing 'build/bdist.macosx-10.12-x86_64/egg' (and everything under it)
Processing myProject-0.0.1.dev0-py3.6.egg
Removing /path/myProject/venv/lib/python3.6/site-packages/myProject-0.0.1.dev0-py3.6.egg
Copying myProject-0.0.1.dev0-py3.6.egg to /path/myProject/venv/lib/python3.6/site-packages
myProject 0.0.1.dev0 is already the active version in easy-install.pth
Installing mycli script to /path/myProject/venv/bin

Installed /path/myProject/venv/lib/python3.6/site-packages/myProject-0.0.1.dev0-py3.6.egg
Processing dependencies for myProject==0.0.1.dev0
Searching for docopt==0.6.2
Best match: docopt 0.6.2
Adding docopt 0.6.2 to easy-install.pth file

Using /path/myProject/venv/lib/python3.6/site-packages
Finished processing dependencies for myProject==0.0.1.dev0

pip show 也向我展示了预期的结果：

? pip show myProject
Name: myProject
Version: 0.0.1.dev0
Location: /path/myProject/venv/lib/python3.6/site-packages/myProject-0.0.1.dev0-py3.6.egg
Requires: docopt

然而ModuleNotFoundError: No module named 'myProject'，当我执行时总是会弹出错误mycli。

我将非常感谢任何指针。

Answer 1

我找到了我的问题的解决方案，我认为这是对PEP 420 -- Implicit Namespace Packages的误解。

此页面指出，自 Python 3.3 起：

在查找名为"foo"的模块或包时，对于父路径中的每个目录：

• 如果找到 <directory> /foo/__init__.py，则导入并返回常规包。
• 如果不是，但是 <directory> /foo被找到并且是一个目录，它被记录下来并且扫描继续在父路径中的下一个目录。

如果扫描完成而没有返回模块或包，并且至少记录了一个目录，则会创建一个命名空间包。新的命名空间包：

• 将 __path__ 属性设置为在扫描期间找到并记录的路径字符串的可迭代对象。
• 没有 __file__ 属性。

如pkg_resources文档中所定义：

命名空间包是一个只包含其他包和模块的包，没有自己的直接内容。

我的包裹，正如我所描述的，属于那个类别，这不是故意的。

在目录__init.py__下添加一个空后，myProject/我看到这在install步骤中发生：

? python setup.py build    
running build
running build_py
creating build/lib
creating build/lib/myProject
copying myProject/__init__.py -> build/lib/myProject
copying myProject/cli.py -> build/lib/myProject

前：

>>> myProject.__path__
_NamespacePath(['/path/myProject'])
>>> myProject.__file__
AttributeError: module 'myProject' has no attribute '__file__'

后：

>>> myProject.__path__
['/path/myProject']
>>> myProject.__file__
'/path/myProject/__init__.py'